The advent of widely available public computer networks, and particularly public networks capable of supporting multimedia functions such as the Internet, presents a great opportunity for consumers and content providers such as music publishers. Such networks afford content providers increased access to an ever growing market. Consumers benefit from improved access to information and greater convenience. Moreover, in some cases, the digital nature of the information received over a network is preferable to more conventional modes such as printed media. For example, digital sheet music can be printed to replicate its printed media counterpart. Additionally, the digital sheet music can be directly processed by audio and video playback programs, as well as by a variety of digital musical instruments and equipment such as Musical Instrument Digital Interface (MIDI) devices.
Despite this potential, content providers have been reluctant to embrace this market in many cases. One reason for this reluctance has been a perceived threat that access to proprietary subject matter such as copyrighted music over a public network will erode ownership interests in and revenues from such subject matter. The concern is that unscrupulous persons will wrongfully access such subject matter or that authorized users, having rightfully accessed the subject matter, will thereafter distribute the subject matter in contravention of the content providers' rights. Although such possibilities exist in connection with other modes of distribution, public network distribution is thought by some to present peculiar dangers due to the ease with which widespread distribution can be accomplished, e.g., via bulletin boards and the like.
Indeed, conventional computer security systems developed to control access to restricted access data are not well-suited to address these concerns of content providers. For example, access password systems are somewhat effective in limiting access to designated information, but do not afford protection once the information is transmitted from the server system to a public network. Encryption systems have been devised to prevent use of information that is wrongfully intercepted as a result of transmission over a network. In this regard, in key-based encryption systems, authorized clients are provided with a decryption key. The protected information is then transmitted in encrypted form to prevent use by any intercepting party. The authorized client receives the encrypted information and uses the decryption key to decrypt the information. Unfortunately, such encryption systems generally do not provide adequate safeguards to discourage the authorized clients from subsequently redistributing the protected information.